IP addressing – the dotted sets of numbers that define the virtual locations of every website, node, and IoT device on the network – goes back to the earliest days of the internet. To many, it seems complicated and technical, since all its flavours seem to do the same thing. But there are differences in the ways IP addresses are assigned and used: public and private, static and dynamic, and more.
One of the most important pairings is public and private – and using the wrong one for your use case can cost you big. So we thought we’d clarify the difference – with a look at the pros, cons, and use cases for private and public. Starting with what they actually mean.
Private IP via NAT: for when internet connectivity is all that's needed
In the good old days of internet networking (they weren’t actually that good, to be honest!), everything on the network had its own, publicly-routable IP address – a unique set of numbers known colloquially as a “dotted quad”. But a fairly short dotted quad has a fairly small set of unique numbers in it, known as the “address space” – and as the internet evolved and the number of devices exploded, it became necessary to make that limited address space go further. Much further.
IPv6 (up from the earlier IPv4) lengthened the numbers, thus expanding the address space. But IPv4 remained in common use, so another way to make the best use of IP addresses came into play: NAT, or Network Address Translation, allowing for “private” IP addresses to come into play: ones you couldn’t “see” on the internet. And since they weren’t public, ones that could be reused across many, many private networks.